US4571258A - Recovery of aluminium scrap - Google Patents

Recovery of aluminium scrap Download PDF

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Publication number
US4571258A
US4571258A US06/612,309 US61230984A US4571258A US 4571258 A US4571258 A US 4571258A US 61230984 A US61230984 A US 61230984A US 4571258 A US4571258 A US 4571258A
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US
United States
Prior art keywords
scrap
molten aluminium
molten
aluminium
metal
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Expired - Fee Related
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US06/612,309
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English (en)
Inventor
Pervez J. F. Bamji
Nigel P. Fitzpatrick
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Rio Tinto Alcan International Ltd
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Alcan International Ltd Canada
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Assigned to ALCAN INTERNATIONAL LIMITED A COMPANY INCORPORATED OF CANADA reassignment ALCAN INTERNATIONAL LIMITED A COMPANY INCORPORATED OF CANADA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BAMJI, PERVEZ JAL F., FITZPATRICK, NIGEL P.
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B21/00—Obtaining aluminium
    • C22B21/0084—Obtaining aluminium melting and handling molten aluminium
    • C22B21/0092—Remelting scrap, skimmings or any secondary source aluminium
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to the recovery of aluminium scrap (including aluminium alloy scrap).
  • Light gauge aluminium scrap such as beverage can scrap
  • has a very low bulk density for example 15-100 kgs/m 3 .
  • Batch addition of such scrap to a melting furnace therefore presents problems both in the bulk of the batch and in the storage of decoated scrap prior to addition to the melting furnace charge.
  • the present invention contemplates the addition of decoated scrap to a melting furnace system in a substantially continuous manner, either truly continuously or in the form of separate small batches of proportions which do not choke the charging zone and thereby impede the stirring pattern on top of the furnace.
  • Processes for the decoating of coated aluminium scrap on a continuous scale are already known.
  • One continuous process for decoating shredded aluminium beverage cans has already been described in copending U.S. Patent Application Ser. No. 412,273.
  • the metal In continuous decoating processes the metal is heated to temperatures of the order to 500°-550° C. and substantial heat economy can be achieved by transfer of the hot decoated metal to a remelting stage without the intermediate cooling inevitably involved in collecting a substantial batch of decoated scrap.
  • a channel-type induction furnace is relatively efficient in terms of power consumption for melting scrap aluminium and recent developments in that type of furnace permit very high energy inputs to be achieved, and it is thus a highly suitable type of furnace for melting large quantities of scrap.
  • One suitable form of channel-type induction furnace is described in U.S. Pat. Nos. 3,092,682 and 3,595,979.
  • the channel-type induction furnace exerts very little stirring of the molten metal in the surface region and is therefore ineffective to submerge low density decoated aluminium scrap in the molten metal in the furnace at a rate comparable to the rate at which it can supply heat for melting the scrap.
  • a process for the recovery of coated light gauge aluminium scrap comprises continuously decoating the scrap, substantially continuously supplying the decoated scrap, preferably without intermediate cooling, to a body of molten aluminium maintained above a channel-type induction furnace heating stage, stirring such body of molten aluminium to submerge the solid decoated scrap therein, supplying heat to said molten aluminium by means of said channel-type induction heating stage and withdrawing molten aluminium from said body of molten aluminium substantially continuously.
  • heat is supplied to molten metal by means of submerged twin induction coils located in the lower part of the furnace.
  • Metal enters the heating stage of the furnace through a throat and flows downwardly into an axial channel located between the twin coils, flows outwardly through a horizontal passage below the coils and returns upwardly through a pair of spaced channels, located outside the induction coils and arranged symmetrically in relation to the axial down flow passage. Since the heating stage of the furnace is separated from the main body of metal in the hearth of the furnace by the throat there is relatively little movement of metal in the hearth.
  • useful surface turbulence of metal in the main hearth of the furnace is created by magnetodynamic means so as to establish currents which will either suck down metal shreds fed onto the surface of the molten metal along the axis of the hearth or produce strong down flows at the peripheral wall of the hearth which will cause the metal shreds to flow outwards to the hearth wall and be sucked down along the hearth wall.
  • the withdrawal of molten aluminium is preferably effected substantially continuously so as to maintain the level of such body of molten aluminium substantially constant. This level should ideally match the ability of the furnace to give optimum metal recovery.
  • the metal recovery in a coreless induction furnace is a function of the stirring patterns generated in the body of the molten metal.
  • the stirring patterns themselves can alter according to the level of metal that is contained in the furnace above the coil.
  • optimum recovery of decoated beverage can shreds was obtained when the metal level in the coreless induction furnace was approximately 120-125% of the coil height.
  • One very effective system for carrying out the invention is a coreless induction submergence device superimposed on a channel-type induction heating stage.
  • the coreless induction submergence device then provides the stirring action necessary for the submersion for the decoated scrap shreds at a relatively low energy input and generates sufficient heat to hold a body of molten metal at a desired temperature of the order of 720° C., from which it may be drawn off on a substantially continuous scale, matched to the rate of scrap supply.
  • This arrangement allows metal in the coreless induction submergence stage to be held at a substantially constant level at which it is most efficient in its action as a furnace. It has been found that the efficiency, in terms of metal recovery, of coreless induction furnaces is very sensitive to metal level and that the metal level should be held substantially above the top of the furnace coils.
  • a linear induction motor trough conveyor is a very satisfactory device for carrying out the removal of molten metal substantially continuously.
  • This device comprises a trough for metal flow arranged at a small angle to the horizontal and a linear induction motor arranged beneath the floor of the trough to impel the flow of a stream of molten metal upwardly in the trough, which in this instance may lead to a holding furnace.
  • one or more trough conveyors act on the body of molten metal to provide supplementary stirring action by impelling it either in a radial direction or in a tangential direction.
  • One or more of the trough conveyors may be periodically reversed for drawing off the molten metal or a separate trough conveyor may be employed for removing molten metal essentially continuously.
  • the channel velocity should be higher than 0.5 meters/sec. with 1 to 2 meters/sec. being preferable.
  • gas chlorine or inert gas
  • the high metal velocity and resultant turbulence ensures that the gas is dispersed in finely divided bubble form to perform its sparging function (removal of alkali- and alkaline earth-metals and/or removal of hydrogen).
  • This is a definite advantage over the conventional introduction of gas at the entrance to the heating channels for cleaning purposes.
  • the presence of large volumes of gas in the metal in the heating channels would restrict its conductivity and thus restrict the energy input.
  • the injection of gas at the outlet ends of the channels permits larger volumes of gas to be introduced effectively, while the cleanliness of the channels is maintained by the high velocity metal flow therethrough.
  • FIG. 1 illustrates diagrammatically one form of apparatus for putting the present invention into effect.
  • FIG. 2 illustrates an alternative form of melting furnace system.
  • FIG. 3 shows a plan view of an alternative form of scrap metal submergence system for the melting furnace system of FIG. 2.
  • a continuous stream of shredded aluminium scrap, preferably decoated, is supplied to the melting furnace 1 from a continuous decoating system, constructed and operated, for example, as described in copending U.S. Patent Application Ser. No. 412,273.
  • the melting furnace comprises an upper, coreless induction furnace stage 2 and a lower channeltype induction heating stage 3.
  • the molten metal is maintained at a substantially constant level in the furnace stage 2 by means of a linear induction motorpowered trough conveyor 4, which discharges a stream of molten metal to a holding furnace 5, which may be of any suitable type, but for metal cleanliness reasons is very conveniently a low-power induction furnace.
  • the indicated system makes best use of the characteristics of the coreless induction furnace 2 and maintains the molten metal level substantially above the top of the coils 6 of the coreless induction furnace stage 2.
  • the furnace 2 acts as an electromagnetic stirrer for the submergence of the shreds of solid aluminium scrap and as a means of supplying a proportion of the heat requirements of the system.
  • the melting furnace 11 comprises a holder 12 and channel-type induction heating stage 14.
  • the holder is provided with a pair of diametrically opposed trough conveyors 15 which impel molten metal towards the centre of the holder thereby producing an axial suction zone into which shredded scrap fragments 17 can be charged via a hopper 18.
  • Periodically one or more of the linear induction motors of the trough conveyors 15 can be switched on in reverse thus enabling molten metal to flow outwards into a holding furnace.
  • the hopper 18 is surrounded by a fume extraction hood 19. In this arrangement it may be desirable to employ a central baffle plate to direct the molten metal downwardly beneath the hopper 18.
  • gas injection passages 21 are arranged for injection of gas at the outlet end of each of the heating channels 22, as already described.
  • the same arrangement may also be employed in the induction furnace stage 3 of FIG. 1.
  • aluminium scrap may be melted at a rate of 5 tonnes/hr with an energy input of 300-500 Kwh/tonne of scrap depending upon whether the scrap is cold or is received at a temperature of the order of 550° C. from the decoating process.
  • the coreless induction furnace could be rated at 500 kw and the channel-type induction furnace have two inductions each rated at 1000 kw.
  • trough conveyors 25 equipped with linear induction motors, are arranged tangentially with the melting furnace holder 12.
  • the trough conveyors 25 are reversible, as in the construction of FIG. 2, and may be operated to draw metal off from the holder 12 to holding furnace 5 or may be operated to drive metal in the reverse direction and thus establish a vortex in the holder 12, into which the scrap metal shreds are supplied for submergence and down flow to the channel-type induction heating stage 14.
  • the melting furnace prefferably be constructed with a submergence stage and a channel-type induction heating stage arranged coaxially with one another.
  • a submergence stage and a channel-type induction heating stage arranged coaxially with one another.
  • two or more channel-type induction heaters arranged side-by-side beneath a single submergence stage.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Processing Of Solid Wastes (AREA)
  • Furnace Details (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Chemical Treatment Of Metals (AREA)
US06/612,309 1983-05-26 1984-05-21 Recovery of aluminium scrap Expired - Fee Related US4571258A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8314577A GB8314577D0 (en) 1983-05-26 1983-05-26 Recovery of aluminium scrap
GB8314577 1983-05-26

Publications (1)

Publication Number Publication Date
US4571258A true US4571258A (en) 1986-02-18

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ID=10543403

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/612,309 Expired - Fee Related US4571258A (en) 1983-05-26 1984-05-21 Recovery of aluminium scrap

Country Status (12)

Country Link
US (1) US4571258A (enrdf_load_stackoverflow)
EP (1) EP0129975B1 (enrdf_load_stackoverflow)
JP (1) JPS59229426A (enrdf_load_stackoverflow)
AT (1) ATE23564T1 (enrdf_load_stackoverflow)
AU (1) AU563641B2 (enrdf_load_stackoverflow)
BR (1) BR8402531A (enrdf_load_stackoverflow)
CA (1) CA1220347A (enrdf_load_stackoverflow)
DE (1) DE3461300D1 (enrdf_load_stackoverflow)
ES (1) ES8600417A1 (enrdf_load_stackoverflow)
GB (1) GB8314577D0 (enrdf_load_stackoverflow)
MY (1) MY100605A (enrdf_load_stackoverflow)
ZA (1) ZA843790B (enrdf_load_stackoverflow)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0400925A3 (en) * 1989-05-29 1991-01-23 Alcan International Limited Process and apparatus for melting contaminated metalliferous scrap material
US5032171A (en) * 1989-12-14 1991-07-16 Aluminum Company Of America Aluminum scrap recovery by inductively moving molten metal
WO1999041951A1 (de) * 1998-02-12 1999-08-19 INDUGA Industrieöfen und Giesserei-Anlagen GmbH & Co. KG Verfahren und induktionsofen zum schmelzen von kleinstückigem metall- und/oder metallhaltigem schüttgut
US20040129402A1 (en) * 2002-11-13 2004-07-08 Boulet Alain Renaud Magnesium die casting system
US20070062336A1 (en) * 2005-08-04 2007-03-22 Alcan Rhenalu Method for recycling aluminum-lithium-type alloy scrap
US20080034923A1 (en) * 2004-04-22 2008-02-14 Xiao-Guang Chen Recycling Method For Al-Bac Composite Materials
CN102175080A (zh) * 2011-01-14 2011-09-07 杭州因达电炉有限公司 一种有芯无芯感应炉
FR3126425A1 (fr) * 2021-08-31 2023-03-03 Constellium Issoire Procédé de recyclage de scrap en alliage d’aluminium eco-responsable
EP4396386A1 (fr) * 2021-08-31 2024-07-10 Constellium Issoire Ligne de refusion de scrap en alliage d'aluminium éco-responsable

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0238538A (ja) * 1988-07-27 1990-02-07 Asahi Tec Corp アルミニウム合金切粉再溶解装置および方法
FR2672620A1 (fr) * 1991-02-11 1992-08-14 Thermco Procede et installation de recuperation par fusion de metaux non ferreux sous forme divisee.
JP3568568B2 (ja) * 1994-01-17 2004-09-22 本田技研工業株式会社 自動車用アルミニウム合金製品屑のリサイクル法
DE19541993A1 (de) * 1995-11-10 1997-05-15 Junker Gmbh O Anwendung eines Verfahrens zum Behandeln von Metallschmelzen
DE102021121030A1 (de) * 2021-08-12 2023-02-16 Otto Junker Gesellschaft mit beschränkter Haftung Vorrichtung zur induktiven Erwärmung einer Metallschmelze, Mehrkammerschmelzofen zum Schmelzen von Schrott aus Metall und Verfahren zum Schmelzen von Schrott aus Metall

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3579324A (en) * 1968-11-18 1971-05-18 Inductotherm Corp Method for induction melting of fine particles
US3790145A (en) * 1970-06-10 1974-02-05 Graenges Essem Ab Device in a melting or holding furnace for facilitating the charging thereof
GB1533420A (en) * 1977-08-25 1978-11-22 Electricity Council Melting of aluminium and aluminium alloys
US4264060A (en) * 1977-02-25 1981-04-28 Automated Production Systems Corporation Apparatus for treating metallic scrap in the recovery of metal therefrom

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3092682A (en) * 1960-03-24 1963-06-04 Ajax Magnethermic Corp Submerged resistor type induction furnaces and methods and processes therefor
DE1800124A1 (de) * 1968-10-01 1970-05-27 Aeg Elotherm Gmbh Verfahren zur Erhoehung der Dosiergenauigkeit des fluessigen Metalls in einer elektromagnetischen Foerderrinne
US3595979A (en) * 1970-01-28 1971-07-27 Ajax Magnethermic Corp Induction furnaces
US4375885A (en) * 1980-02-13 1983-03-08 Shinko Electric Co., Ltd. Reverberatory furnace
GB2085925B (en) * 1980-10-20 1985-01-09 Alcan Int Ltd Decorating of aluminium scrap

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3579324A (en) * 1968-11-18 1971-05-18 Inductotherm Corp Method for induction melting of fine particles
US3790145A (en) * 1970-06-10 1974-02-05 Graenges Essem Ab Device in a melting or holding furnace for facilitating the charging thereof
US4264060A (en) * 1977-02-25 1981-04-28 Automated Production Systems Corporation Apparatus for treating metallic scrap in the recovery of metal therefrom
GB1533420A (en) * 1977-08-25 1978-11-22 Electricity Council Melting of aluminium and aluminium alloys

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5122181A (en) * 1989-05-29 1992-06-16 Alcan International Limited Process and apparatus for melting contaminated metalliferrous scrap material
AU626098B2 (en) * 1989-05-29 1992-07-23 Alcan International Limited Process and apparatus for melting contaminated metalliferous scrap material
EP0400925A3 (en) * 1989-05-29 1991-01-23 Alcan International Limited Process and apparatus for melting contaminated metalliferous scrap material
US5032171A (en) * 1989-12-14 1991-07-16 Aluminum Company Of America Aluminum scrap recovery by inductively moving molten metal
WO1999041951A1 (de) * 1998-02-12 1999-08-19 INDUGA Industrieöfen und Giesserei-Anlagen GmbH & Co. KG Verfahren und induktionsofen zum schmelzen von kleinstückigem metall- und/oder metallhaltigem schüttgut
US6240120B1 (en) * 1998-02-12 2001-05-29 Induga Industrieofen Und Giesserei-Anlagen Gmbh & Co. Kg Inductive melting of fine metallic particles
US20040129402A1 (en) * 2002-11-13 2004-07-08 Boulet Alain Renaud Magnesium die casting system
US6926066B2 (en) * 2002-11-13 2005-08-09 Alain Renaud Boulet Magnesium die casting system
US7550029B2 (en) 2004-04-22 2009-06-23 Alcan International Limited Recycling method for Al—B4C composite materials
US20080034923A1 (en) * 2004-04-22 2008-02-14 Xiao-Guang Chen Recycling Method For Al-Bac Composite Materials
US20070062336A1 (en) * 2005-08-04 2007-03-22 Alcan Rhenalu Method for recycling aluminum-lithium-type alloy scrap
US7550028B2 (en) * 2005-08-04 2009-06-23 Alcan Rhenalu Method for recycling aluminum-lithium-type alloy scrap
CN102175080A (zh) * 2011-01-14 2011-09-07 杭州因达电炉有限公司 一种有芯无芯感应炉
FR3126425A1 (fr) * 2021-08-31 2023-03-03 Constellium Issoire Procédé de recyclage de scrap en alliage d’aluminium eco-responsable
WO2023031546A1 (fr) * 2021-08-31 2023-03-09 Constellium Issoire Procédé de recyclage de scrap en alliage d'aluminium eco-responsable
EP4396386A1 (fr) * 2021-08-31 2024-07-10 Constellium Issoire Ligne de refusion de scrap en alliage d'aluminium éco-responsable

Also Published As

Publication number Publication date
JPS59229426A (ja) 1984-12-22
EP0129975A1 (en) 1985-01-02
MY100605A (en) 1990-12-15
BR8402531A (pt) 1985-04-02
EP0129975B1 (en) 1986-11-12
DE3461300D1 (en) 1987-01-02
ZA843790B (en) 1984-12-24
ES532819A0 (es) 1985-10-01
AU563641B2 (en) 1987-07-16
ES8600417A1 (es) 1985-10-01
JPS6227139B2 (enrdf_load_stackoverflow) 1987-06-12
GB8314577D0 (en) 1983-06-29
AU2877884A (en) 1984-11-29
ATE23564T1 (de) 1986-11-15
CA1220347A (en) 1987-04-14

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